In synthesis of a sine waveform, it is known to use direct digital frequency synthesis by switching a number of weighted current cells on the basis of a digital code signal. The performance of a corresponding waveform synthesizer can be defined by the spurious-free dynamic range (SFDR) of the generated sine wave at a certain frequency. The SFDR is typically limited by limited output impedance of current sources used in the current cells of the waveform synthesizer. The effect of the limited output impedance is that, with increasing number of activated current cells, the output current of each current cell decreases from its nominal value. The output signal of the waveform synthesizer will therefore deviate from an ideal sine waveform.
Accordingly, there is a need for techniques which allow for accurate digital waveform synthesis.